1. Field of the Invention
2. Discussion of the Background
In an ATN architecture, an air/ground exchange is required on the initiative of the aircraft, to allow the application software to communicate. This exchange is manifested as an exchange of requests designated by the names xe2x80x9cCM-Logon.requestxe2x80x9d for a query in the air/ground direction and xe2x80x9cCM-Logon.confimxe2x80x9d for a query in the ground/air direction, CM-Logon being the abbreviation for the expression xe2x80x9cContext Managementxe2x80x9d.
The xe2x80x9cCM-Logon.requestxe2x80x9d request allows an airborne system to indicate to the ground those applications which are supported, and especially to which addresses the latter may be appended. This procedure enables ground application software to be apprised of the software of the airborne applications. On receipt of this request, a ground station stores the information relating to the accessibility of the applications of the aeroplane in a database.
Conversely, the xe2x80x9cCM-Logon.responsexe2x80x9d request makes it possible:
a) for a ground system to indicate to an aircraft that it has received its request properly;
b) to indicate in return a list of applications available on the ground, as well as their addresses. As before, on receipt of the response, the aircraft stores the accessibility information for the software of the ground applications in a database.
This procedure is managed by a piece of application software known by the abbreviation CMA standing for the expression xe2x80x9cContext Management Applicationxe2x80x9d set up within ground entities and within a counterpart entity on board the aircraft. The CMA application software makes it possible to disseminate information relating to other applications of the type of those known by the abbreviations ADS, CPDLC, FIS, NMa, AOC, etc., and whose functionalities are described in the appendix. Thus, for example, before a CMA procedure is carried out successfully, the CPDLC entities which manage digital communications between air controller and pilot cannot communicate, although this becomes possible afterwards.
However, the problem remains unresolved for the CMA of the aircraft which initiates the procedure which is not a priori apprised of the ground address to which its request should be sent.
In the current systems, there is provision to involve the pilot such that the address of the ground CMA to be contacted is entered explicitly into the database of the CMA of the aircraft.
The object of the invention is to render this procedure automatic so as to absolve the pilot of any involvement.
Accordingly, the subject of the invention is a process for the automatic searching by an aircraft for a communication address of a ground entity to be contacted of an ATN network, each address being coded according to a hierarchical binary tree structure comprising several fields, a first field for identifying the network and the subsequent fields for identifying entities of the network of the type consisting:
in storing in a database of the aircraft the identities the addresses of a specified number of ground communication centers of an ATN network,
in the aircraft transmitting the identity of the aircraft as known by its address to ground routers of an overflown ATN network,
in the ground router which was able to be apprised of the identity of the aircraft transmitting its own address,
characterized in that it consists in determining in the aircraft the address of the communication center (CMA) to be contacted from the identity of the router which it receives by comparing the received address of the router with those of the addresses contained in the database, retaining as address that which, given the hierarchical tree structure of the addresses, has the largest number of characters in common with the address of the ground router.
The main advantage of the process according to the invention is that it makes it possible to absolve the pilot of the need to input the initial CMA address. In view of its simplicity, it is fairly inexpensive to implement.
By utilizing the hierarchical structure of the NSAP address fields of the ATN networks, the process also allows custom-sizing of the database of the CMA centers. This sizing can be done according to one or a combination of the following criteria:
Capacity of the host structure accommodating this database: the larger the capacities, the more entries one may have.
Type of aircraft: medium-haul aircraft for example could have much slimmer bases than long-haul aircraft. The slimming being achieved as a function of the geographical zone covered by the scheduled flights of the aircraft (e.g. an aircraft dedicated to European traffic need not be apprised of the CMA centers of the Asian zone). Moreover, the format of the entries of the base of CMA centers being very simple, it can readily be stored in a space allowing easy updating. It may very readily be imagined that in the first instance updates may be accomplished by a technician. Further into the future, updating could be accomplished via the ATN network itself (i.e. with no physical intervention on the aircraft).
It may thus be noted that it is not absolutely necessary to have strictly the same information in all the bases carried on board the aircraft. This could enable the ATN network administrators to share out the aircraft over a finite number of centers (for example European aircraft essentially over European centers and then, to a lesser extent, over American and/or Asiatic centers and conversely for the other aircraft; or else military aircraft over certain centers, civil aircraft over others, etc.).